The object of this study is to use mutants of Drosophila melanogaster to study the development and function of the nervous system. A genetic screen using mass-mating techniques is being used to isolate putative neurological mutants on the X-chromosome and autosomes by selecting for adults with temperature-induced locomotor defects. Two additional screening procedures have been develped. One involves a search for revertants and/or suppressors of a known neurological mutant. The second involves a search for temperature-sensitive larval paralysis mutants. Characterization of two previously isolated mutants is in progress. It is proposed that stress-sensitive mutants (such as bang-sensitive) are unusually sensitive to a chemical released during stress. To test this model, parameters affecting paralysis will be defined, relative sensitivity to amine released during stress will be defined, and an analysis of genetic mosaics will be extended using internal histochemical markers. Fate-mapping studies using internal markers are also in progress to determine the foci of the temperature-sensitive paralysis mutant shibirets. In addition, the contour modification of this procedure is being used to define the tissues responsible for the different temperature-induced lethalities exhibited by this mutant. Electrophysiological studies involving recordings from larval tissues will be used to analyze neural function at both permissive and nonpermissive temperatures.